1. Field of the Invention
This invention relates generally to signal means and more particularly to signal means adapted to be attached to a motor vehicle for indicating a low pressure condition of ground-engaging pneumatic tires.
2. Description of the Prior Art
In recent years the use of tubeless tires has become more prevalent. Although tubleless tires are superior to former tube-type tires in many respects, it has been found that they often develop slow leaks. The slow leaks result from many reasons. Perhaps the most frequent reason is deformation of the wheel rim. This causes the seal between the tire and the rim to become less than perfect, and permits air to leak from the tire. Various forms of vehicles equipped with pneumatic tires can be operated with one of the pneumatic tires thereof in a deflated position without the driver of the vehicles being aware of the deflated tire condition.
It is advisable to maintain proper air pressure in the tires for the purpose of assuring proper vehicle riding qualities, for preventing rapid tire wear and for eliminating the safety hazard presented by improper inflation. Furthermore, operation of a deflated tire for more than short distances causes the tire to be excessively flexed and to generate heat. This excessive flexing and heat can quickly render the tire irreparably damaged. Accordingly, a need exists for a low tire pressure warning system which may be readily mounted on various forms of vehicles and utilized to indicate to the driver when one of the pneumatic tires thereof or the pneumatic tires of a towed trailer has become deflated.
Various forms of low tire pressure warning systems have been heretofore designed, but most of these systems are not constructed in a manner whereby they may be readily mounted upon various vehicles equipped with different types and sizes of axles.
Furthermore, the prior systems do not incorporate features to prevent damage to the warning system components themselves in event of a rapid tire deflation or a slow leak of the tire while the vehicle is left unattended. Earlier devices typically depend upon a switch lever or feeler which makes contact with the ground to indicate a low tire pressure. However, the switch activation lever or feeler may become bent, or be abraded off by contacting the road at high speeds. Another shortcoming of earlier devices is that a slow deflation while unattended causes direct compressive force to be exerted upon the switching means upon vertical contact with the road surface. Consequent damage to the switch means may be more costly than the mere deflation of the tire, and the activation lever or feeler would need to be repaired or replaced in order to render the device once again useful for its intended purpose.
Examples of various forms of previous low tire pressure warning systems are disclosed in U.S. Pat. Nos. 2,258,334, 2,469,931, 2,640,119, 2,740,007 and 3,610,851.
The main object of this invention is to provide a low tire pressure warning system including visual and audible signal generators actuatable in response to the sensing of low tire pressure.
A further object of the present invention is to provide a low tire pressure warning system which may be utilized on operator driven vehicles as well as on vehicles trailed behind operator driven vehicles.
It is a still further object of this invention to provide a system in accordance with the preceding objects readily adapted for use on vehicles having different size tires.
Yet another object of the present invention is to provide a low tire pressure warning system of the aforesaid nature resistant to damage caused by contacting the road surface in the event of a tire pressure leak, and which may be easily installed onto various forms of vehicles after their manufacture.
An additional object of this invention is to provide a low tire pressure warning system of the aforesaid nature of simple, durable construction amenable to low cost manufacture.
These objects and other objects and advantages of the invention will be apparent from the following description.